b3aa1d9c63
Revert the bespoke __prompt()/__prompt2() function mechanism from issue #09 and return to stock Lua's _PROMPT/_PROMPT2 globals (which already support dynamic prompts via __tostring metatables). Set default _PROMPT = "lush> " in doREPL if not already defined by config.
59 lines
1.5 KiB
Markdown
59 lines
1.5 KiB
Markdown
# 09 — Programmable prompt
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**Status:** open
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**Blocked by:** #08
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Users should be able to customize the shell prompt by defining a Lua function, similar to how other shells use `PS1`/`PROMPT_COMMAND`/`precmd`.
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## Design
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- The prompt is generated by calling a global Lua function (e.g. `__prompt()`)
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- The function returns a string which is used as the prompt
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- If the function is not defined or errors, fall back to a sensible default
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## Default prompt
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A built-in default prompt is provided (implemented on the C side) until the user overrides `__prompt()` in their config. The default could be something like:
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```
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lush>
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```
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or include the current directory:
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```
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~/Code/project>
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```
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## User customization
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Users override the prompt in their config (`~/.config/lush/config`):
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```lua
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function __prompt()
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return $PWD .. "> "
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end
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```
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Or with colours/git info/etc:
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```lua
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function __prompt()
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local cwd = $PWD or "?"
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local branch = `git branch --show-current 2>/dev/null`
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local git = (branch.code == 0) and " (" .. branch.stdout:gsub("\n","") .. ")" or ""
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return cwd .. git .. "> "
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end
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```
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## Implementation considerations
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- The REPL loop (in `lua.c`) calls `__prompt()` before each input line
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- If `__prompt` is not a function or the call fails, use the default C-side prompt
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- The function runs in the normal Lua state so it has access to all globals, env vars, commands, etc.
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## Open questions
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- Should there be a separate `__continuation_prompt()` for multiline input?
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- Should the prompt function receive any arguments (e.g. exit code of last command)?
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